feat: trend pullback preview TP per DCA leg with unified stop loss across exchanges

Co-authored-by: Cursor <cursoragent@cursor.com>

strategy_trend_register.py

@@ -1093,15 +1093,11 @@ def load_trend_page_context(conn, request_obj, cfg: dict) -> dict[str, Any]:
         ).fetchone()
         now_ms = int(time.time() * 1000)
         if pr and int(pr["expires_at_ms"] or 0) >= now_ms:
+            from strategy_trend_lib import build_trend_preview_level_rows
+
             trend_preview = _row(cfg, pr)
             preview_expires_ms = int(pr["expires_at_ms"])
-            try:
-                grid = json.loads(trend_preview.get("grid_prices_json") or "[]")
-                legs = json.loads(trend_preview.get("leg_amounts_json") or "[]")
-            except Exception:
-                grid, legs = [], []
-            for i, pair in enumerate(zip(grid, legs), 1):
-                trend_preview_levels.append({"i": i, "price": pair[0], "contracts": pair[1]})
+            trend_preview, trend_preview_levels = build_trend_preview_level_rows(trend_preview)
         elif pr:
             trend_preview_expired = True
     return {